rac 环境搭建单实例文件系统DG + broke配置
2017-05-12 01:09
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说明：
1. 本文档是在测试环境中进行的。环境架构为双节点RAC+单节点DG。
2. 本文档主要测试RAC环境下的准备切换。包括：dataguard的搭建过程，switch over过程和 fail over过程。
3. 由于本测试环境数据量很少，且主库服务器所剩空间不多，所以采用直接复制备库的方式搭建DG环境。
--主库的两个实例：
demo1 192.168.52.231
demo2 192.168.52.232
--备库：
dg_demo 192.168.52.235
--搭建最大性能的物理standby
--配置主库：
1．开启主库的强制日志功能：
alter database force logging;
select force_logging from v$database;
2．修改主库的参数文件：
alter system set LOG_ARCHIVE_CONFIG='DG_CONFIG=(demo,dg_demo)' scope=both;
alter system set LOG_ARCHIVE_DEST_1='LOCATION=+DGARCH/DEMO/ARCHIVELOG/ VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=demo' scope=both;
alter system set LOG_ARCHIVE_DEST_2='SERVICE=dg_demo LGWR ASYNC NOAFFIRM VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) COMPRESSION=ENABLE DB_UNIQUE_NAME=dg_demo' scope=both;
alter system set LOG_ARCHIVE_DEST_STATE_1=ENABLE scope=both;
alter system set LOG_ARCHIVE_DEST_STATE_2=ENABLE scope=both;
alter system set LOG_ARCHIVE_MAX_PROCESSES=10 scope=both;
alter system set FAL_SERVER=dg_demo;
alter system set FAL_CLIENT=demo;
alter system set db_file_name_convert='/oradata/demo/datafile/','+DGDATA/demo/datafile/','/oradata/demo/datafile/','+DGDATA/demo/tempfile/' scope=spfile; --必须停库（此参数主从切换使用，可以先不配置）
alter system set log_file_name_convert='/oradata/demo/logfile/','+DGDATA/demo/onlinelog/','/oradata/demo/logfile/','+DGARCH/demo/onlinelog/' scope=spfile;--必须停库（此参数主从切换使用，可以先不配置）
alter system set standby_file_management=auto;
3. 在tnsnames.ora中添加如下条目：
vim tnsnames.ora
---------------------------------------------------------------
demo1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.231)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = demo)
(INSTANCE_NAME = demo1)
)
)
demo2 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.232)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = demo)
(INSTANCE_NAME = demo2)
)
)
dg_demo =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.235)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = dg_demo)
)
)
4．将主库的参数文件和口令文件拷贝到备库并更名：
SQL> create pfile from spfile;
参数文件：initdg_demo
口令文件：orapwdg_demo
oracle@rac1:/opt/oracle/11gR2/db/dbs> scp initdemo1.ora test-rac-dg:/opt/oracle/11gR2/db/dbs/initdg_demo.ora
oracle@rac1:/opt/oracle/11gR2/db/dbs> scp orapwdemo1 test-rac-dg:/opt/oracle/11gR2/db/dbs/orapwdg_demo
--配置备库：
5. 修改备库的参数文件：
--------------------------------
*.audit_file_dest='/opt/oracle/11gR2/admin/demo/adump'
*.audit_trail='db'
*.cluster_database=false
*.compatible='11.2.0.0.0'
*.control_files='/oradata/demo/controlfile/control01.ctl'
*.db_block_size=8192
*.db_create_file_dest='/oradata/demo/datafile'
*.db_domain=''
*.db_file_name_convert='+DGDATA/demo/datafile/','/oradata/demo/datafile/','+DGDATA/demo/tempfile/','/oradata/demo/datafile/'
*.log_file_name_convert='+DGDATA/demo/onlinelog/','/oradata/demo/logfile/','+DGARCH/demo/onlinelog/','/oradata/demo/logfile/'
*.db_name='demo'
*.db_unique_name='dg_demo'
*.diagnostic_dest='/opt/oracle/11gR2'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=demoXDB)'
*.job_queue_processes=1000
*.log_archive_config='DG_CONFIG=(demo,dg_demo)'
*.fal_client='dg_demo'
*.fal_server='demo1','demo2'
*.log_archive_dest_1='LOCATION=/oradata/demo/archivelog/ VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=dg_demo'
*.log_archive_dest_2='SERVICE=demo LGWR ASYNC NOAFFIRM VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) COMPRESSION=ENABLE DB_UNIQUE_NAME=demo'
*.log_archive_format='%t_%s_%r.arc'
*.log_archive_max_processes=10
*.open_cursors=500
*.processes=150
*.remote_login_passwordfile='exclusive'
*.standby_file_management='AUTO'
*.thread=1
*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS1'
---------------------------------------------------------------------------
6. 准备相关目录：
mkdir -p /opt/oracle/11gR2/admin/demo/adump
mkdir /oradata/demo/archivelog
mkdir /oradata/demo/datafile
mkdir /oradata/demo/logfile
mkdir /oradata/demo/controlfile
7．配置备库的网络:（netmgr）
（1）配置网络监听：
vim listener.ora
---------------------------------------------
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = dg_demo)
(ORACLE_HOME = /opt/oracle/11gR2/db)
(SID_NAME = dg_demo)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.235)(PORT = 1521))
)
ADR_BASE_LISTENER = /opt/oracle/11gR2
（2）为备库准备tnsnames.ora文件
备库的tnsnames.ora文件从主库拷贝
8．启动备库到nomount:
export ORACLE_SID=dg_demo
sqlplus / as sysdba
startup nomount
9．测试网络是否通：
sqlplus /nolog
conn sys/oracle@demo1 as sysdba
conn sys/oracle@demo2 as sysdba
conn sys/oracle@dg_demo as sysdba
10. 还原备库:(在两个节点都可以完成）
rman target sys/oracle@demo1 auxiliary sys/oracle@dg_demo
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
allocate auxiliary channel c5 type disk;
duplicate target database for standby from active database;
release channel c1;
release channel c2;
release channel c3;
release channel c4;
release channel c5;
}
--还原完成之后，备库已经为mount状态。
SQL> select status from v$instance;
STATUS
------------
MOUNTED
12. 为备库增加standby日志：
alter database add standby logfile thread 1 group 7 '/oradata/demo/logfile/stdredo7a.log' size 52428800;
alter database add standby logfile thread 1 group 8 '/oradata/demo/logfile/stdredo8a.log' size 52428800;
alter database add standby logfile thread 1 group 9 '/oradata/demo/logfile/stdredo9a.log' size 52428800;
alter database add standby logfile thread 2 group 10 '/oradata/demo/logfile/stdredo10a.log' size 52428800;
alter database add standby logfile thread 2 group 11 '/oradata/demo/logfile/stdredo11a.log' size 52428800;
alter database add standby logfile thread 2 group 12 '/oradata/demo/logfile/stdredo12a.log' size 52428800;
alter database add standby logfile member
'/oradata/demo/logfile/stdredo7b.log' to group 7,
'/oradata/demo/logfile/stdredo8b.log' to group 8,
'/oradata/demo/logfile/stdredo9b.log' to group 9,
'/oradata/demo/logfile/stdredo10b.log' to group 10,
'/oradata/demo/logfile/stdredo11b.log' to group 11,
'/oradata/demo/logfile/stdredo12b.log' to group 12;
在主库也增加standby日志：
alter database add standby logfile thread 1 group 5 '+data/demo/onlinelog/standby5.log' size 52428800;
alter database add standby logfile thread 1 group 6 '+data/demo/onlinelog/standby6.log' size 52428800;
alter database add standby logfile thread 1 group 7 '+data/demo/onlinelog/standby7.log' size 52428800;
alter database add standby logfile thread 2 group 8 '+data/demo/onlinelog/standby8.log' size 52428800;
alter database add standby logfile thread 2 group 9 '+data/demo/onlinelog/standby9.log' size 52428800;
alter database add standby logfile thread 2 group 10 '+data/demo/onlinelog/standby10.log' size 52428800;
13.启动备库(默认为只读模式)：
alter database open;
14. 在备库开启日志实时应用模式:
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
验证是否成功：
（1）查看主库远程归档是否报错：（会有延迟）
select dest_id,status,error from v$archive_dest where dest_id=2;
（2）通过警报日志监控备库日志应用情况:
cd $ORACLE_BASE/diag/rdbms/dg_demo/dg_demo/trace
tailf alert_dg_demo.log --永远等待主库的current组。
（3）在备库查看日志应用情况:
select sequence#,name,applied from v$archived_log order by 1;
select * from (select thread#,sequence#,applied from v$archived_log where thread#=1 order by sequence# desc) where rownum<=5
union
select * from (select thread#,sequence#,applied from v$archived_log where thread#=2 order by sequence# desc) where rownum<=5;
--在主库查看
SELECT THREAD#,MAX(sequence#) from v$archived_log group by thread#;
select * from (select thread#,dest_id,sequence#,applied from v$archived_log where thread#=1 and dest_id=2 order by sequence# desc) where rownum<=5
union
select * from (select thread#,dest_id,sequence#,applied from v$archived_log where thread#=2 and dest_id=2 order by sequence# desc) where rownum<=5;
--查看v$standby_log视图，发现每个实例只有且只能有一组日志处于active状态。
SQL> select group#,thread#,sequence#,archived,status from v$standby_log;
GROUP# THREAD# SEQUENCE# STATUS
---------- ---------- ---------- ----------
7 1 710 ACTIVE
8 2 400 ACTIVE
9 2 0 UNASSIGNED
10 2 0 UNASSIGNED
11 1 0 UNASSIGNED
12 1 0 UNASSIGNED
============================================================================================================
主从切换
--RAC环境下主备切换只能有一个实例是活动的，其他实例必须关闭。这里我们关闭demo2节点。
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo2
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
--在RAC节点一将主库切换到备库
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
demo1
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
SQL> alter database commit to switchover to physical standby;
Database altered.
SQL> shutdown immediate;
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 738200072 bytes
Database Buffers 41943040 bytes
Redo Buffers 2637824 bytes
Database mounted.
--将备库切换到主库
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
--启动备库（rac）的实例1
SQL> alter database open;
Database altered.
SQL> select status from v$instance;
STATUS
------------
OPEN
--启动备库（RCA）的实例2
oracle@rac2:~> sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Wed Jun 25 15:04:56 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 763365896 bytes
Database Buffers 16777216 bytes
Redo Buffers 2637824 bytes
Database mounted.
Database opened.
--启动主库（原备库）
SQL> alter database open;
Database altered.
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
--启动备库(231,232)的日志应用（MRP进程）
--注意，如果standby 是RAC环境，MRP只能在一个实例上执行，这个RAC的恢复操作一样，而其他实例只能运行RFS.
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
--主库(235)查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库(231,232)查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
select thread#,sequence#,dest_id,name,applied from v$archived_log where sequence#>1000 order by 1,2,3 ;
===================================================================================================
--switchover切换回最初状态
--关闭备库的其中一个节点
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo2
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
--将主库（235）切换到备库
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO STANDBY
SQL> alter database commit to switchover to physical standby;
Database altered.
SQL> shutdown immediate;
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 738200072 bytes
Database Buffers 41943040 bytes
Redo Buffers 2637824 bytes
Database mounted.
--在备库的实例demo1（231）上将备库切换到主库
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo1
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
--启动实例1
SQL> alter database open;
Database altered.
SQL> select status from v$instance;
STATUS
------------
OPEN
--启动实例2
oracle@rac2:~> sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Wed Jun 25 15:04:56 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 763365896 bytes
Database Buffers 16777216 bytes
Redo Buffers 2637824 bytes
Database mounted.
Database opened.
--启动备库（235）
alter database open;
--在备库启动日志应用
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
--主库查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
select thread#,sequence#,dest_id,name,applied from v$archived_log where sequence#>1000 order by 1,2,3;
================================================================================================
failover
--failover
--模拟主库实例损坏，这里将两个实例一起停掉
srvctl stop database -d demo -o immediate
1） 查看是否有日志 GAP：
SQL> SELECT UNIQUE THREAD#,MAX(SEQUENCE#) OVER(PARTITION BY THREAD#) LAST FROM V$ARCHIVED_LOG;
SQL> SELECT THREAD#,LOW_SEQUENCE#,HIGH_SEQUENCE# FROM V$ARCHIVE_GAP;
2） 如果有，则拷贝过来
3） 手工的注册这些日志：
SQL> ALTER DATABASE REGISTER LOGFILE '路径';
--本次实验没有GAP.
--使用有GAP,则使用如下命令在备库应用这些日志：
--alter database recover managed standby database cancel;
--recover standby database until cancel;
--停掉日志应用
SQL> alter database recover managed standby database cancel;
Database altered.
--现在我们来将备库切换到主库
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH FORCE;
SQL> SELECT DATABASE_ROLE FROM V$DATABASE;
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;
SQL> ALTER DATABASE OPEN; 或者 shutdown immediate+startup
--以上的步骤是常规的方法，如果用这个方法的时候报错：
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY
*
ERROR at line 1:
ORA-16139: media recovery required
--错误提示需要做恢复，如果在上述步骤中已经在备库应用过日志。则尝试强制Failover一下看看：
shutdown immediate
startup mount;
alter database activate standby database;
alter database open;
==============================================================
failover 重新搭建DG
--使用原参数文件将备库（231,232）启动到nomount
srvctl start database -d demo -o nomount
--对主库（原备库）进行全备份:
rman target /
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
backup as compressed backupset database format '/home/oracle/rmanbak/Full_%d_%I_%s_%p_%T.bkp';
backup current controlfile format '/home/oracle/rmanbak/ctl_%d_%I_%s_%p_%T.bkp';
release channel c1;
release channel c2;
release channel c3;
release channel c4;
}
--将主库(原备库)的全备拷贝到备库的相同目录：
oracle@rac2:~/rmanbak> scp 192.168.52.235:/home/oracle/rmanbak/Full*.bkp .
--将备库恢复到mount状态
rman target /
restore standby controlfile from '/home/oracle/rmanbak/ctl_dTEST_889759476_59_1';
--将备库启动到mount
alter database mount;
--还原备库
rman target /
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
restore database;
recover database;
release channel c1;
release channel c2;
release channel c3;
release channel c4;
}
--在备库应用日志
alter database recover managed standby database using current logfile disconnect from session;
--打开备库
SQL> alter database recover managed standby database cancel;
Database altered.
SQL> alter database open;
Database altered.
--将连个节点重新启动
srvctl stop database -d test
srvctl start database -d test
--将RAC切换成主库，即回到最初的状态（双实例RAC+单实例DG)
####################################################################################################
failover 开启数据库闪回功能 （不需要重新搭建dg）停机
主从数据库都需要打开flashback database
SQL> show parameter recovery
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string +data
db_recovery_file_dest_size big integer 1G
recovery_parallelism integer 0
select flashback_on from v$database; 在主从都看 查看是否开启
shut immediate
startup mount
alter database flashback on; //开启闪回
fast overfail主从数据库必须置为最大可用状态，如果不是也不要着急，一会用dgmgrl来切成最大可用。
select protection_mode,database_role,protection_level from v$database
另外，主从数据库都要使用spfile：
show parameter spfile
----模拟failover主库（rac库）
srvctl stop database -d demo -o immediate
---备库（dg_test）
[oracle@dg flash]$ dgmgrl
DGMGRL for Linux: Version 11.2.0.4.0 - 64bit Production
Copyright (c) 2000, 2009, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
DGMGRL> connect
Username: sys
Password:
将备库切换成主库
DGMGRL> failover to dg_test
原来的备库成为主库
DGMGRL> show configuration
Configuration - dg_rac
Protection Mode: MaxPerformance
Databases:
dg_test - Primary database
test - Physical standby database (disabled)
ORA-16661: the standby database needs to be reinstated
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL> reinstate database test;
原来主库变为备库
srvctl start database -d test
--检查
select database_role,open_mode,protection_mode,force_logging,FLASHBACK_ON from v$database;
--主库(235)查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库(231,232)查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
监控主从同步状况
select to_char(SYSDATE,'yyyymmdd hh24:mi:ss') CTIME,NAME,VALUE,DATUM_TIME
from V$DATAGUARD_STATS
WHERE NAME LIKE '%lag';
=================================================================================================
dgmgrl 配置
说明：
本实验主库是rac环境 test （demo）
从库是单实例 dg_test （dg_demo）
1、rac环境需要将u01/app/oracle/product/11.2.0/dbhome_1/dbs/dr1rac.dat 文件共享
主库：（rac环境）
SQL> alter system set dg_broker_start=false scope=both sid='*';
SQL> show parameter dg_broker_start
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_start boolean FALSE
SQL> alter system set dg_broker_config_file1='+data/test/dr1rac.dat' sid='*';
System altered.
SQL> alter system set dg_broker_config_file2='+data/test/dr2rac.dat' sid='*';
System altered.
SQL> alter system set dg_broker_start=true scope=both sid='*';
System altered.
SQL> show parameter dg
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_config_file1 string +data/rac/dr1rac.dat
dg_broker_config_file2 string +data/rac/dr2rac.dat
dg_broker_start boolean TRUE
备库：
SQL> alter system set dg_broker_start=true scope=both;
SQL> show parameter dg
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_start boolean TRUE
SQL>
主库：
[oracle@rac2 ~]$dgmgrl
DGMGRL> connect
Username: sys
Password:
Connected.
DGMGRL> create configuration 'dg_rac' as primary database is 'test' connect identifier is 'test';
create configuration '随意起名' as primary database is 'db_unique_name' connect identifier is 'tnsname.ora里连接主库';
DGMGRL> add database 'test' as connect identifier is 'dg_test' maintained as physical;
add database 'db_unique_name' as connect identifier is 'tnsname.ora连接备库' maintained as physical;
DGMGRL> show configuration
Configuration - dg_rac
Protection Mode: MaxPerformance
Databases:
test - Primary database
dg_test - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
DISABLED
DGMGRL> enable configuration;
DGMGRL> show configuration
DGMGRL> enable database dg_test
DGMGRL> enable database test
主从切换（rac节点必须停止一节点 ）
DGMGRL> switchover to dg_test
Performing switchover NOW, please wait...
Operation requires a connection to instance "dg_test" on database "dg_test"
Connecting to instance "dg_test"...
Connected.
New primary database "dg_test" is opening...
Operation requires startup of instance "test2" on database "test"
Starting instance "test2"...
Unable to connect to database
ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
Failed.
Warning: You are no longer connected to ORACLE.
Please complete the following steps to finish switchover:
start up instance "test2" of database "test"
failover 切换
dgmgrl failover切换命令
DGMGRL> failover to dg_test
DGMGRL> reinstate database test
test：
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PHYSICAL STANDBY
dg_test：
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
启动主库停掉的实例
从库需要手工startup启动数据库
监控主从同步状况
select to_char(SYSDATE,'yyyymmdd hh24:mi:ss') CTIME,NAME,VALUE,DATUM_TIME
from V$DATAGUARD_STATS
WHERE NAME LIKE '%lag';
============================================================================================
DG的三大模式
– Maximum protection 最大保护
dgmgrl 切换
验证：
select DATABASE_ROLE,PROTECTION_MODE,PROTECTION_LEVEL from v$database;
DATABASE_ROLE PROTECTION_MODE PROTECTION_LEVEL
---------------- -------------------- --------------------
PHYSICAL STANDBY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY
配置快速故障转移（不推荐使用）
5、修改快速故障转移的延迟时间(默认为30秒，有些少!):
DGMGRL> edit configuration set property FastStartFailoverThreshold=10;
主库终止 从库延迟10s后从库再启动
6、启动快速故障转移:
DGMGRL> edit configuration set protection mode as MAXAvailability;
DGMGRL> enable configuration;
DGMGRL> enable fast_start failover;
Enabled.
快速故障转移必须在最大可用模式下配置
1. 本文档是在测试环境中进行的。环境架构为双节点RAC+单节点DG。
2. 本文档主要测试RAC环境下的准备切换。包括：dataguard的搭建过程，switch over过程和 fail over过程。
3. 由于本测试环境数据量很少，且主库服务器所剩空间不多，所以采用直接复制备库的方式搭建DG环境。
--主库的两个实例：
demo1 192.168.52.231
demo2 192.168.52.232
--备库：
dg_demo 192.168.52.235
--搭建最大性能的物理standby
--配置主库：
1．开启主库的强制日志功能：
alter database force logging;
select force_logging from v$database;
2．修改主库的参数文件：
alter system set LOG_ARCHIVE_CONFIG='DG_CONFIG=(demo,dg_demo)' scope=both;
alter system set LOG_ARCHIVE_DEST_1='LOCATION=+DGARCH/DEMO/ARCHIVELOG/ VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=demo' scope=both;
alter system set LOG_ARCHIVE_DEST_2='SERVICE=dg_demo LGWR ASYNC NOAFFIRM VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) COMPRESSION=ENABLE DB_UNIQUE_NAME=dg_demo' scope=both;
alter system set LOG_ARCHIVE_DEST_STATE_1=ENABLE scope=both;
alter system set LOG_ARCHIVE_DEST_STATE_2=ENABLE scope=both;
alter system set LOG_ARCHIVE_MAX_PROCESSES=10 scope=both;
alter system set FAL_SERVER=dg_demo;
alter system set FAL_CLIENT=demo;
alter system set db_file_name_convert='/oradata/demo/datafile/','+DGDATA/demo/datafile/','/oradata/demo/datafile/','+DGDATA/demo/tempfile/' scope=spfile; --必须停库（此参数主从切换使用，可以先不配置）
alter system set log_file_name_convert='/oradata/demo/logfile/','+DGDATA/demo/onlinelog/','/oradata/demo/logfile/','+DGARCH/demo/onlinelog/' scope=spfile;--必须停库（此参数主从切换使用，可以先不配置）
alter system set standby_file_management=auto;
3. 在tnsnames.ora中添加如下条目：
vim tnsnames.ora
---------------------------------------------------------------
demo1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.231)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = demo)
(INSTANCE_NAME = demo1)
)
)
demo2 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.232)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = demo)
(INSTANCE_NAME = demo2)
)
)
dg_demo =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.235)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = dg_demo)
)
)
4．将主库的参数文件和口令文件拷贝到备库并更名：
SQL> create pfile from spfile;
参数文件：initdg_demo
口令文件：orapwdg_demo
oracle@rac1:/opt/oracle/11gR2/db/dbs> scp initdemo1.ora test-rac-dg:/opt/oracle/11gR2/db/dbs/initdg_demo.ora
oracle@rac1:/opt/oracle/11gR2/db/dbs> scp orapwdemo1 test-rac-dg:/opt/oracle/11gR2/db/dbs/orapwdg_demo
--配置备库：
5. 修改备库的参数文件：
--------------------------------
*.audit_file_dest='/opt/oracle/11gR2/admin/demo/adump'
*.audit_trail='db'
*.cluster_database=false
*.compatible='11.2.0.0.0'
*.control_files='/oradata/demo/controlfile/control01.ctl'
*.db_block_size=8192
*.db_create_file_dest='/oradata/demo/datafile'
*.db_domain=''
*.db_file_name_convert='+DGDATA/demo/datafile/','/oradata/demo/datafile/','+DGDATA/demo/tempfile/','/oradata/demo/datafile/'
*.log_file_name_convert='+DGDATA/demo/onlinelog/','/oradata/demo/logfile/','+DGARCH/demo/onlinelog/','/oradata/demo/logfile/'
*.db_name='demo'
*.db_unique_name='dg_demo'
*.diagnostic_dest='/opt/oracle/11gR2'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=demoXDB)'
*.job_queue_processes=1000
*.log_archive_config='DG_CONFIG=(demo,dg_demo)'
*.fal_client='dg_demo'
*.fal_server='demo1','demo2'
*.log_archive_dest_1='LOCATION=/oradata/demo/archivelog/ VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=dg_demo'
*.log_archive_dest_2='SERVICE=demo LGWR ASYNC NOAFFIRM VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) COMPRESSION=ENABLE DB_UNIQUE_NAME=demo'
*.log_archive_format='%t_%s_%r.arc'
*.log_archive_max_processes=10
*.open_cursors=500
*.processes=150
*.remote_login_passwordfile='exclusive'
*.standby_file_management='AUTO'
*.thread=1
*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS1'
---------------------------------------------------------------------------
6. 准备相关目录：
mkdir -p /opt/oracle/11gR2/admin/demo/adump
mkdir /oradata/demo/archivelog
mkdir /oradata/demo/datafile
mkdir /oradata/demo/logfile
mkdir /oradata/demo/controlfile
7．配置备库的网络:（netmgr）
（1）配置网络监听：
vim listener.ora
---------------------------------------------
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = dg_demo)
(ORACLE_HOME = /opt/oracle/11gR2/db)
(SID_NAME = dg_demo)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.52.235)(PORT = 1521))
)
ADR_BASE_LISTENER = /opt/oracle/11gR2
（2）为备库准备tnsnames.ora文件
备库的tnsnames.ora文件从主库拷贝
8．启动备库到nomount:
export ORACLE_SID=dg_demo
sqlplus / as sysdba
startup nomount
9．测试网络是否通：
sqlplus /nolog
conn sys/oracle@demo1 as sysdba
conn sys/oracle@demo2 as sysdba
conn sys/oracle@dg_demo as sysdba
10. 还原备库:(在两个节点都可以完成）
rman target sys/oracle@demo1 auxiliary sys/oracle@dg_demo
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
allocate auxiliary channel c5 type disk;
duplicate target database for standby from active database;
release channel c1;
release channel c2;
release channel c3;
release channel c4;
release channel c5;
}
--还原完成之后，备库已经为mount状态。
SQL> select status from v$instance;
STATUS
------------
MOUNTED
12. 为备库增加standby日志：
alter database add standby logfile thread 1 group 7 '/oradata/demo/logfile/stdredo7a.log' size 52428800;
alter database add standby logfile thread 1 group 8 '/oradata/demo/logfile/stdredo8a.log' size 52428800;
alter database add standby logfile thread 1 group 9 '/oradata/demo/logfile/stdredo9a.log' size 52428800;
alter database add standby logfile thread 2 group 10 '/oradata/demo/logfile/stdredo10a.log' size 52428800;
alter database add standby logfile thread 2 group 11 '/oradata/demo/logfile/stdredo11a.log' size 52428800;
alter database add standby logfile thread 2 group 12 '/oradata/demo/logfile/stdredo12a.log' size 52428800;
alter database add standby logfile member
'/oradata/demo/logfile/stdredo7b.log' to group 7,
'/oradata/demo/logfile/stdredo8b.log' to group 8,
'/oradata/demo/logfile/stdredo9b.log' to group 9,
'/oradata/demo/logfile/stdredo10b.log' to group 10,
'/oradata/demo/logfile/stdredo11b.log' to group 11,
'/oradata/demo/logfile/stdredo12b.log' to group 12;
在主库也增加standby日志：
alter database add standby logfile thread 1 group 5 '+data/demo/onlinelog/standby5.log' size 52428800;
alter database add standby logfile thread 1 group 6 '+data/demo/onlinelog/standby6.log' size 52428800;
alter database add standby logfile thread 1 group 7 '+data/demo/onlinelog/standby7.log' size 52428800;
alter database add standby logfile thread 2 group 8 '+data/demo/onlinelog/standby8.log' size 52428800;
alter database add standby logfile thread 2 group 9 '+data/demo/onlinelog/standby9.log' size 52428800;
alter database add standby logfile thread 2 group 10 '+data/demo/onlinelog/standby10.log' size 52428800;
13.启动备库(默认为只读模式)：
alter database open;
14. 在备库开启日志实时应用模式:
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
验证是否成功：
（1）查看主库远程归档是否报错：（会有延迟）
select dest_id,status,error from v$archive_dest where dest_id=2;
（2）通过警报日志监控备库日志应用情况:
cd $ORACLE_BASE/diag/rdbms/dg_demo/dg_demo/trace
tailf alert_dg_demo.log --永远等待主库的current组。
（3）在备库查看日志应用情况:
select sequence#,name,applied from v$archived_log order by 1;
select * from (select thread#,sequence#,applied from v$archived_log where thread#=1 order by sequence# desc) where rownum<=5
union
select * from (select thread#,sequence#,applied from v$archived_log where thread#=2 order by sequence# desc) where rownum<=5;
--在主库查看
SELECT THREAD#,MAX(sequence#) from v$archived_log group by thread#;
select * from (select thread#,dest_id,sequence#,applied from v$archived_log where thread#=1 and dest_id=2 order by sequence# desc) where rownum<=5
union
select * from (select thread#,dest_id,sequence#,applied from v$archived_log where thread#=2 and dest_id=2 order by sequence# desc) where rownum<=5;
--查看v$standby_log视图，发现每个实例只有且只能有一组日志处于active状态。
SQL> select group#,thread#,sequence#,archived,status from v$standby_log;
GROUP# THREAD# SEQUENCE# STATUS
---------- ---------- ---------- ----------
7 1 710 ACTIVE
8 2 400 ACTIVE
9 2 0 UNASSIGNED
10 2 0 UNASSIGNED
11 1 0 UNASSIGNED
12 1 0 UNASSIGNED
============================================================================================================
主从切换
--RAC环境下主备切换只能有一个实例是活动的，其他实例必须关闭。这里我们关闭demo2节点。
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo2
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
--在RAC节点一将主库切换到备库
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
demo1
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
SQL> alter database commit to switchover to physical standby;
Database altered.
SQL> shutdown immediate;
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 738200072 bytes
Database Buffers 41943040 bytes
Redo Buffers 2637824 bytes
Database mounted.
--将备库切换到主库
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
--启动备库（rac）的实例1
SQL> alter database open;
Database altered.
SQL> select status from v$instance;
STATUS
------------
OPEN
--启动备库（RCA）的实例2
oracle@rac2:~> sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Wed Jun 25 15:04:56 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 763365896 bytes
Database Buffers 16777216 bytes
Redo Buffers 2637824 bytes
Database mounted.
Database opened.
--启动主库（原备库）
SQL> alter database open;
Database altered.
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
--启动备库(231,232)的日志应用（MRP进程）
--注意，如果standby 是RAC环境，MRP只能在一个实例上执行，这个RAC的恢复操作一样，而其他实例只能运行RFS.
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
--主库(235)查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库(231,232)查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
select thread#,sequence#,dest_id,name,applied from v$archived_log where sequence#>1000 order by 1,2,3 ;
===================================================================================================
--switchover切换回最初状态
--关闭备库的其中一个节点
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo2
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
--将主库（235）切换到备库
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO STANDBY
SQL> alter database commit to switchover to physical standby;
Database altered.
SQL> shutdown immediate;
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 738200072 bytes
Database Buffers 41943040 bytes
Redo Buffers 2637824 bytes
Database mounted.
--在备库的实例demo1（231）上将备库切换到主库
SQL> select INSTANCE_NAME from v$instance;
INSTANCE_NAME
----------------
demo1
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
--启动实例1
SQL> alter database open;
Database altered.
SQL> select status from v$instance;
STATUS
------------
OPEN
--启动实例2
oracle@rac2:~> sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Wed Jun 25 15:04:56 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 784998400 bytes
Fixed Size 2217464 bytes
Variable Size 763365896 bytes
Database Buffers 16777216 bytes
Redo Buffers 2637824 bytes
Database mounted.
Database opened.
--启动备库（235）
alter database open;
--在备库启动日志应用
alter database recover managed standby database using current logfile disconnect from session;
select process,status from v$managed_standby;
--主库查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
select thread#,sequence#,dest_id,name,applied from v$archived_log where sequence#>1000 order by 1,2,3;
================================================================================================
failover
--failover
--模拟主库实例损坏，这里将两个实例一起停掉
srvctl stop database -d demo -o immediate
1） 查看是否有日志 GAP：
SQL> SELECT UNIQUE THREAD#,MAX(SEQUENCE#) OVER(PARTITION BY THREAD#) LAST FROM V$ARCHIVED_LOG;
SQL> SELECT THREAD#,LOW_SEQUENCE#,HIGH_SEQUENCE# FROM V$ARCHIVE_GAP;
2） 如果有，则拷贝过来
3） 手工的注册这些日志：
SQL> ALTER DATABASE REGISTER LOGFILE '路径';
--本次实验没有GAP.
--使用有GAP,则使用如下命令在备库应用这些日志：
--alter database recover managed standby database cancel;
--recover standby database until cancel;
--停掉日志应用
SQL> alter database recover managed standby database cancel;
Database altered.
--现在我们来将备库切换到主库
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH FORCE;
SQL> SELECT DATABASE_ROLE FROM V$DATABASE;
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;
SQL> ALTER DATABASE OPEN; 或者 shutdown immediate+startup
--以上的步骤是常规的方法，如果用这个方法的时候报错：
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY
*
ERROR at line 1:
ORA-16139: media recovery required
--错误提示需要做恢复，如果在上述步骤中已经在备库应用过日志。则尝试强制Failover一下看看：
shutdown immediate
startup mount;
alter database activate standby database;
alter database open;
==============================================================
failover 重新搭建DG
--使用原参数文件将备库（231,232）启动到nomount
srvctl start database -d demo -o nomount
--对主库（原备库）进行全备份:
rman target /
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
backup as compressed backupset database format '/home/oracle/rmanbak/Full_%d_%I_%s_%p_%T.bkp';
backup current controlfile format '/home/oracle/rmanbak/ctl_%d_%I_%s_%p_%T.bkp';
release channel c1;
release channel c2;
release channel c3;
release channel c4;
}
--将主库(原备库)的全备拷贝到备库的相同目录：
oracle@rac2:~/rmanbak> scp 192.168.52.235:/home/oracle/rmanbak/Full*.bkp .
--将备库恢复到mount状态
rman target /
restore standby controlfile from '/home/oracle/rmanbak/ctl_dTEST_889759476_59_1';
--将备库启动到mount
alter database mount;
--还原备库
rman target /
run{
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
allocate channel c4 type disk;
restore database;
recover database;
release channel c1;
release channel c2;
release channel c3;
release channel c4;
}
--在备库应用日志
alter database recover managed standby database using current logfile disconnect from session;
--打开备库
SQL> alter database recover managed standby database cancel;
Database altered.
SQL> alter database open;
Database altered.
--将连个节点重新启动
srvctl stop database -d test
srvctl start database -d test
--将RAC切换成主库，即回到最初的状态（双实例RAC+单实例DG)
####################################################################################################
failover 开启数据库闪回功能 （不需要重新搭建dg）停机
主从数据库都需要打开flashback database
SQL> show parameter recovery
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string +data
db_recovery_file_dest_size big integer 1G
recovery_parallelism integer 0
select flashback_on from v$database; 在主从都看 查看是否开启
shut immediate
startup mount
alter database flashback on; //开启闪回
fast overfail主从数据库必须置为最大可用状态，如果不是也不要着急，一会用dgmgrl来切成最大可用。
select protection_mode,database_role,protection_level from v$database
另外，主从数据库都要使用spfile：
show parameter spfile
----模拟failover主库（rac库）
srvctl stop database -d demo -o immediate
---备库（dg_test）
[oracle@dg flash]$ dgmgrl
DGMGRL for Linux: Version 11.2.0.4.0 - 64bit Production
Copyright (c) 2000, 2009, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
DGMGRL> connect
Username: sys
Password:
将备库切换成主库
DGMGRL> failover to dg_test
原来的备库成为主库
DGMGRL> show configuration
Configuration - dg_rac
Protection Mode: MaxPerformance
Databases:
dg_test - Primary database
test - Physical standby database (disabled)
ORA-16661: the standby database needs to be reinstated
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL> reinstate database test;
原来主库变为备库
srvctl start database -d test
--检查
select database_role,open_mode,protection_mode,force_logging,FLASHBACK_ON from v$database;
--主库(235)查询是否报错
select dest_id,status,error from v$archive_dest where dest_id=2;
--备库(231,232)查询日志是否成功应用
select thread#,sequence#,dest_id,name,applied from v$archived_log order by 1,2,3;
监控主从同步状况
select to_char(SYSDATE,'yyyymmdd hh24:mi:ss') CTIME,NAME,VALUE,DATUM_TIME
from V$DATAGUARD_STATS
WHERE NAME LIKE '%lag';
=================================================================================================
dgmgrl 配置
说明：
本实验主库是rac环境 test （demo）
从库是单实例 dg_test （dg_demo）
1、rac环境需要将u01/app/oracle/product/11.2.0/dbhome_1/dbs/dr1rac.dat 文件共享
主库：（rac环境）
SQL> alter system set dg_broker_start=false scope=both sid='*';
SQL> show parameter dg_broker_start
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_start boolean FALSE
SQL> alter system set dg_broker_config_file1='+data/test/dr1rac.dat' sid='*';
System altered.
SQL> alter system set dg_broker_config_file2='+data/test/dr2rac.dat' sid='*';
System altered.
SQL> alter system set dg_broker_start=true scope=both sid='*';
System altered.
SQL> show parameter dg
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_config_file1 string +data/rac/dr1rac.dat
dg_broker_config_file2 string +data/rac/dr2rac.dat
dg_broker_start boolean TRUE
备库：
SQL> alter system set dg_broker_start=true scope=both;
SQL> show parameter dg
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_start boolean TRUE
SQL>
主库：
[oracle@rac2 ~]$dgmgrl
DGMGRL> connect
Username: sys
Password:
Connected.
DGMGRL> create configuration 'dg_rac' as primary database is 'test' connect identifier is 'test';
create configuration '随意起名' as primary database is 'db_unique_name' connect identifier is 'tnsname.ora里连接主库';
DGMGRL> add database 'test' as connect identifier is 'dg_test' maintained as physical;
add database 'db_unique_name' as connect identifier is 'tnsname.ora连接备库' maintained as physical;
DGMGRL> show configuration
Configuration - dg_rac
Protection Mode: MaxPerformance
Databases:
test - Primary database
dg_test - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
DISABLED
DGMGRL> enable configuration;
DGMGRL> show configuration
DGMGRL> enable database dg_test
DGMGRL> enable database test
主从切换（rac节点必须停止一节点 ）
DGMGRL> switchover to dg_test
Performing switchover NOW, please wait...
Operation requires a connection to instance "dg_test" on database "dg_test"
Connecting to instance "dg_test"...
Connected.
New primary database "dg_test" is opening...
Operation requires startup of instance "test2" on database "test"
Starting instance "test2"...
Unable to connect to database
ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
Failed.
Warning: You are no longer connected to ORACLE.
Please complete the following steps to finish switchover:
start up instance "test2" of database "test"
failover 切换
dgmgrl failover切换命令
DGMGRL> failover to dg_test
DGMGRL> reinstate database test
test：
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PHYSICAL STANDBY
dg_test：
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
启动主库停掉的实例
从库需要手工startup启动数据库
监控主从同步状况
select to_char(SYSDATE,'yyyymmdd hh24:mi:ss') CTIME,NAME,VALUE,DATUM_TIME
from V$DATAGUARD_STATS
WHERE NAME LIKE '%lag';
============================================================================================
DG的三大模式
– Maximum protection 最大保护
在Maximum protection下， 可以保证从库和主库数据完全一样，做到zero data loss.事务同时在主从两边提交完成，才算事务完成。如果从库宕机或者网络出现问题，主从库不能通讯，主库也立即宕机。在这种方式下，具有最高的保护等级。但是这种模式对主库性能影响很大，要求高速的网络连接。– Maximum availability 最大可用 （推荐）
在Maximum availability模式下，如果和从库的连接正常，运行方式等同Maximum protection模式，事务也是主从库同时提交。如果从库和主库失去联系，则主库自动切换到Maximum performance模式下运行，保证主库具有最大的可用性。– Maximum performance 最大性能
在Maximum performance，主库把归档的 archived log通过arch进程传递给从库，在这种方式下，主库运行性能最高，但是不能保证数据不丢失，且丢失的数据受redo log的大小影响。在redo log过大的情况下，可能一天都没有归档一个日志，可以通过手工切换日志的方式来减小数据的丢失。
dgmgrl 切换
DGMGRL> show database verbose 'demo';
DGMGRL> show database verbose 'dg_demo';c.如果LogXptMode的值为async，就要将其修改为sync
DGMGRL> edit database demo property logxptmode=
DGMGRL> edit database dg_demo set property logxptmode=sync;d.修改完之后再次确认LogXptMode的值，如步骤b e.切换模式（如果切换失败，则再次去确认备库LogXptMode的值）
DGMGRL> edit configuration set protection mode as maxavailability; Succeeded.
验证：
select DATABASE_ROLE,PROTECTION_MODE,PROTECTION_LEVEL from v$database;
DATABASE_ROLE PROTECTION_MODE PROTECTION_LEVEL
---------------- -------------------- --------------------
PHYSICAL STANDBY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY
配置快速故障转移（不推荐使用）
5、修改快速故障转移的延迟时间(默认为30秒，有些少!):
DGMGRL> edit configuration set property FastStartFailoverThreshold=10;
主库终止 从库延迟10s后从库再启动
6、启动快速故障转移:
DGMGRL> edit configuration set protection mode as MAXAvailability;
DGMGRL> enable configuration;
DGMGRL> enable fast_start failover;
Enabled.
快速故障转移必须在最大可用模式下配置
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